U.S. patent application number 13/800590 was filed with the patent office on 2013-10-03 for lighting system and calibration method therefor.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Masanao Kurita.
Application Number | 20130257290 13/800590 |
Document ID | / |
Family ID | 49233987 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130257290 |
Kind Code |
A1 |
Kurita; Masanao |
October 3, 2013 |
LIGHTING SYSTEM AND CALIBRATION METHOD THEREFOR
Abstract
A lighting apparatus has a plurality of light emission block
group and a detection unit for each light emission block group,
wherein light emission blocks selected from different light
emission block groups are grouped as sets, and light emission
blocks belonging to a same set are caused to emit light
simultaneously. The grouping is such that a minimum value, in all
the sets, of a detection value ratio becomes as large as possible,
wherein the detection value ratio is a ratio between an amount of
light due to a light emission from one light emission block
belonging to a light emission block group corresponding to each
detection unit, and an amount of light due to a light emission from
another light emission block emitting light simultaneously with the
one light emission block.
Inventors: |
Kurita; Masanao;
(Isehara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
49233987 |
Appl. No.: |
13/800590 |
Filed: |
March 13, 2013 |
Current U.S.
Class: |
315/152 |
Current CPC
Class: |
H05B 47/10 20200101;
G09G 2320/043 20130101; G09G 2320/0693 20130101; H05B 45/22
20200101; G09G 3/3426 20130101; G09G 2320/0626 20130101; G09G
2320/0233 20130101; G09G 2360/145 20130101 |
Class at
Publication: |
315/152 |
International
Class: |
H05B 37/02 20060101
H05B037/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2012 |
JP |
2012-080967 |
Claims
1. A lighting apparatus comprising: a plurality of light emission
block groups composed of a plurality of light emission blocks, the
emissions of light of which are able to be controlled independently
of one another; and a detection unit that is provided for each of
said light emission block groups, and detects a light emission
characteristic of each of light emission blocks which belong to the
corresponding light emission block group; wherein said plurality of
light emission blocks are grouped in such a manner that sets of
light emission blocks are formed, each one of which is selected
from a plurality of different light emission block groups, with all
said light emission blocks being included in any of the sets; an
obtaining unit is provided which carries out control on all the
sets in a sequential manner, such that a plurality of light
emission blocks belonging to a same set are caused to emit light at
the same time, and a light emission characteristic of each of those
light emission blocks which are caused to emit light at the same
time is obtained by a detection unit corresponding to a light
emission block group to which each of the light emission blocks
emitting light at the same time belongs; and said grouping is
decided in such a manner that a minimum value, in all the sets, of
a detection value ratio becomes as large as possible, wherein the
detection value ratio is a ratio between an amount of light, of the
total amount of light which is received by each of said detection
units at the time when the plurality of light emission blocks
belonging to the same set emit light at the same time, due to an
emission of light from a light emission block belonging to a light
emission block group corresponding to each of said detection units,
and an amount of light, of said total amount of light, due to an
emission of light from another light emission block which emits
light simultaneously with said light emission block.
2. A lighting apparatus comprising: a plurality of light emission
block groups composed of a plurality of light emission blocks, the
emissions of light of which are able to be controlled independently
of one another; and a detection unit group that is provided for
each of said light emission block groups, and is composed of a
plurality of detection units for detecting light emission
characteristics of light emission blocks which belong to the
corresponding light emission block group; wherein said plurality of
light emission blocks are grouped in such a manner that sets of
light emission blocks are formed, each one of which is selected
from a plurality of different light emission block groups, with all
said light emission blocks being included in any of the sets; an
obtaining unit is provided which carries out control on all the
sets in a sequential manner, such that a plurality of light
emission blocks belonging to a same set are caused to emit light at
the same time, and a light emission characteristic of each of those
light emission blocks which are caused to emit light at the same
time is obtained by a detection unit which is the nearest to said
light emission block, among a plurality of detection units
belonging to a detection unit group corresponding to a light
emission block group to which each of the light emission blocks
emitting light at the same time belongs; and said grouping is
decided in such a manner that a minimum value, in all the sets, of
a detection value ratio becomes as large as possible, wherein the
detection value ratio is a ratio between an amount of light, of a
total amount of light which is received by each of said detection
units, at the time when the plurality of light emission blocks
belonging to the same set emit light at the same time, due to an
emission of light from a light emission block belonging to a light
emission block group corresponding to each of said detection units,
and an amount of light, of said total amount of light, due to an
emission of light from another light emission block which emits
light simultaneously with said light emission block.
3. The lighting apparatus as set forth in claim 1, further
comprising: a first light emission block group and a second light
emission block group that are each composed of a plurality of light
emission blocks; a first detection unit for detecting the light
emission characteristic of each of light emission blocks which
belong to said first light emission block group; and a second
detection unit for detecting the light emission characteristic of
each of light emission blocks which belong to said second light
emission block group; wherein the light emission blocks belonging
to said each set comprise two light emission blocks, one of which
is selected from said first light emission block group, and the
other of which is selected from said second light emission block
group; said obtaining unit carries out control on all the sets in a
sequential manner, such that two light emission blocks belonging to
a same set are caused to emit light at the same time, whereby the
light emission characteristic of a light emission block belonging
to said first light emission block group is obtained by said first
detection unit, and the light emission characteristic of a light
emission block belonging to said second light emission block group
is obtained by said second detection unit; and said grouping is
decided by repeating, until all the light emission blocks are
included in any set, at least either one of a first procedure (1)
in which a light emission block, among the light emission blocks
belonging to said first light emission block group, which is the
nearest to said second detection unit, and a light emission block,
among the light emission blocks belonging to said second light
emission block group, which is the nearest to said second detection
unit, are decided as a set, and a second procedure (2) in which a
light emission block, among the light emission blocks belonging to
said first light emission block group, which is the nearest to said
first detection unit, and a light emission block, among the light
emission blocks belonging to said second light emission block
group, which is the nearest to said first detection unit, are
decided as a set.
4. The lighting apparatus as set forth in claim 2, further
comprising: a first light emission block group and a second light
emission block group that are each composed of a plurality of light
emission blocks; a first detection unit group composed of a
plurality of detection units for detecting the light emission
characteristics of light emission blocks which belong to said first
light emission block group; and a second detection unit group
composed of a plurality of detection units for detecting the light
emission characteristics of light emission blocks which belong to
said second light emission block group; wherein the light emission
blocks belonging to said each set comprise two light emission
blocks, one of which is selected from said first light emission
block group, and the other of which is selected from said second
light emission block group; said obtaining unit carries out control
on all the sets in a sequential manner, such that two light
emission blocks belonging to a same set are caused to emit light at
the same time, whereby the light emission characteristic of a light
emission block belonging to said first light emission block group
is obtained by a detection unit which is the nearest to said light
emission block, among the plurality of detection units belonging to
said first detection unit group, and the light emission
characteristic of a light emission block belonging to said second
light emission block group is obtained by a detection unit which is
the nearest to said light emission block, among the plurality of
detection units belonging to said second detection unit group; and
said grouping is decided by repeating, until all the light emission
blocks are included in any set, at least either one of a first
procedure (1) in which a light emission block, among the light
emission blocks belonging to said first light emission block group,
which is the nearest to said second detection unit group, and a
light emission block, among the light emission blocks belonging to
said second light emission block group, which is the nearest to a
detection unit, among the plurality of detection units belonging to
said second detection unit group, which is located at the farthest
from said first light emission block group, are decided as a set,
and a second procedure (2) in which a light emission block, among
the light emission blocks belonging to said first light emission
block group, which is the nearest to a detection unit, among the
plurality of detection units belonging to said first detection unit
group, which is located at the farthest from said second light
emission block group, and a light emission block, among the light
emission blocks belonging to said second light emission block
group, which is the nearest to said first detection unit group, are
decided as a set.
5. The lighting apparatus as set forth in claim 1, further
comprising: a calibration unit configured to correct an amount of
light emission of each light emission block based on a result of a
comparison between a detected value of a light emission
characteristic thereof obtained by said obtaining unit and a target
value thereof.
6. The lighting apparatus as set forth in claim 1, wherein said
detection units each detect at least either brightness or
chromaticity as the light emission characteristic of a light
emission block.
7. A calibration method for a lighting apparatus which includes: a
plurality of light emission block groups composed of a plurality of
light emission blocks, the emissions of light of which are able to
be controlled independently of one another; and a detection unit
that is provided for each of said light emission block groups, and
detects a light emission characteristic of each of light emission
blocks which belong to the corresponding light emission block
group; wherein said plurality of light emission blocks are grouped
in such a manner that sets of light emission blocks are formed,
each one of which is selected from a plurality of different light
emission block groups, with all said light emission blocks being
included in any of the sets; said method comprising: an obtaining
step to carry out control on all the sets in a sequential manner,
such that a plurality of light emission blocks belonging to a same
set are caused to emit light at the same time, and a light emission
characteristic of each of those light emission blocks which are
caused to emit light at the same time is obtained by a detection
unit corresponding to a light emission block group to which each of
the light emission blocks emitting light at the same time belongs;
and a calibration step to correct an amount of light emission of
each light emission block based on a result of a comparison between
a detected value of a light emission characteristic thereof
obtained in said obtaining step and a target value thereof; wherein
said grouping is decided in such a manner that a minimum value, in
all the sets, of a detection value ratio becomes as large as
possible, wherein the detection value ratio is a ratio between an
amount of light, of the total amount of light which is received by
each of said detection units at the time when the plurality of
light emission blocks belonging to the same set emit light at the
same time, due to an emission of light from a light emission block
belonging to a light emission block group corresponding to each of
said detection units, and an amount of light, of said total amount
of light, due to an emission of light from another light emission
block which emits light simultaneously with said light emission
block.
8. A calibration method for a lighting apparatus which includes: a
plurality of light emission block groups composed of a plurality of
light emission blocks, the emissions of light of which are able to
be controlled independently of one another; and a detection unit
group that is provided for each of said light emission block
groups, and is composed of a plurality of detection units for
detecting light emission characteristics of light emission blocks
which belong to the corresponding light emission block group;
wherein said plurality of light emission blocks are grouped in such
a manner that sets of light emission blocks are formed, each one of
which is selected from a plurality of different light emission
block groups, with all said light emission blocks being included in
any of the sets; said method comprising: an obtaining step to carry
out control on all the sets in a sequential manner, such that a
plurality of light emission blocks belonging to a same set are
caused to emit light at the same time, and a light emission
characteristic of each of those light emission blocks which are
caused to emit light at the same time is obtained by a detection
unit which is the nearest to said light emission block, among a
plurality of detection units belonging to a detection unit group
corresponding to a light emission block group to which each of the
light emission blocks emitting light at the same time belongs; and
a calibration step to correct an amount of light emission of each
light emission block based on a result of a comparison between a
detected value of a light emission characteristic thereof obtained
in said obtaining step and a target value thereof; wherein said
grouping is decided in such a manner that a minimum value, in all
the sets, of a detection value ratio becomes as large as possible,
wherein the detection value ratio is a ratio between an amount of
light, of a total amount of light which is received by each of said
detection units, at the time when the plurality of light emission
blocks belonging to the same set emit light at the same time, due
to an emission of light from a light emission block belonging to a
light emission block group corresponding to each of said detection
units, and an amount of light, of said total amount of light, due
to an emission of light from another light emission block which
emits light simultaneously with said light emission block.
9. The calibration method for the lighting apparatus as set forth
in claim 7, the lighting apparatus further comprising: a first
light emission block group and a second light emission block group
that are each composed of a plurality of light emission blocks; a
first detection unit for detecting the light emission
characteristic of each of light emission blocks which belong to
said first light emission block group; and a second detection unit
for detecting the light emission characteristic of each of light
emission blocks which belong to said second light emission block
group; wherein the light emission blocks belonging to said each set
comprise two light emission blocks, one of which is selected from
said first light emission block group, and the other of which is
selected from said second light emission block group; in said
obtaining step, it is carried out control on all the sets in a
sequential manner, such that two light emission blocks belonging to
a same set are caused to emit light at the same time, whereby the
light emission characteristic of a light emission block belonging
to said first light emission block group is obtained by said first
detection unit, and the light emission characteristic of a light
emission block belonging to said second light emission block group
is obtained by said second detection unit; and said grouping is
decided by repeating, until all the light emission blocks are
included in any set, at least either one of a first procedure (1)
in which a light emission block, among the light emission blocks
belonging to said first light emission block group, which is the
nearest to said second detection unit, and a light emission block,
among the light emission blocks belonging to said second light
emission block group, which is the nearest to said second detection
unit, are decided as a set, and a second procedure (2) in which a
light emission block, among the light emission blocks belonging to
said first light emission block group, which is the nearest to said
first detection unit, and a light emission block, among the light
emission blocks belonging to said second light emission block
group, which is the nearest to said first detection unit, are
decided as a set.
10. The calibration method for the lighting apparatus as set forth
in claim 8, the lighting apparatus further comprising: a first
light emission block group and a second light emission block group
that are each composed of a plurality of light emission blocks; a
first detection unit group composed of a plurality of detection
units for detecting the light emission characteristics of light
emission blocks which belong to said first light emission block
group; and a second detection unit group composed of a plurality of
detection units for detecting the light emission characteristics of
light emission blocks which belong to said second light emission
block group; wherein the light emission blocks belonging to said
each set comprise two light emission blocks, one of which is
selected from said first light emission block group, and the other
of which is selected from said second light emission block group;
in said obtaining step, it is carried out control on all the sets
in a sequential manner, such that two light emission blocks
belonging to a same set are caused to emit light at the same time,
whereby the light emission characteristic of a light emission block
belonging to said first light emission block group is obtained by a
detection unit which is the nearest to said light emission block,
among the plurality of detection units belonging to said first
detection unit group, and the light emission characteristic of a
light emission block belonging to said second light emission block
group is obtained by a detection unit which is the nearest to said
light emission block, among the plurality of detection units
belonging to said second detection unit group; and said grouping is
decided by repeating, until all the light emission blocks are
included in any set, at least either one of a first procedure (1)
in which a light emission block, among the light emission blocks
belonging to said first light emission block group, which is the
nearest to said second detection unit group, and a light emission
block, among the light emission blocks belonging to said second
light emission block group, which is the nearest to a detection
unit, among the plurality of detection units belonging to said
second detection unit group, which is located at the farthest from
said first light emission block group, are decided as a set, and a
second procedure (2) in which a light emission block, among the
light emission blocks belonging to said first light emission block
group, which is the nearest to a detection unit, among the
plurality of detection units belonging to said first detection unit
group, which is located at the farthest from said second light
emission block group, and a light emission block, among the light
emission blocks belonging to said second light emission block
group, which is the nearest to said first detection unit group, are
decided as a set.
11. The calibration method for the lighting apparatus as set forth
in claim 7, wherein said detection units each detect at least
either brightness or chromaticity as the light emission
characteristic of a light emission block.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a lighting apparatus and a
calibration method therefor.
[0003] 2. Description of the Related Art
[0004] In general, a color image display apparatus includes a color
liquid crystal panel having light filters, and a backlight
apparatus which is alighting apparatus for irradiating white light
to a back surface of the color liquid crystal panel.
[0005] In the past, as light sources for backlight apparatus,
fluorescent lamps such as cold cathode fluorescent lamps (CCFL:
Cold Cathode Fluorescent Lamps), etc., have mainly been used.
However, in recent years, light emitting diodes (LED: Light
Emitting Diodes), which are advantageous in respect of electric
power consumption, life span, color reproducibility, and
environmental impact, are becoming increasingly used as light
sources of backlight apparatus.
[0006] A backlight apparatus using LEDs as a light source (LED
backlight apparatus) is generally composed of a lot of LEDs.
Japanese patent application laid-open No. 2001-142409 discloses an
LED backlight apparatus which is constructed such that it is
divided into a plurality of light emission blocks, each of which is
composed of one or more LEDs, wherein brightness control is carried
out on these light emission blocks independently of one another.
The electric power consumption of the LED backlight apparatus is
decreased and the contrast of an image is improved, by reducing the
brightnesses of those light emission blocks which irradiate light
on those areas of a color liquid crystal panel in which a dark
image is displayed, among all the display areas thereof. Such
brightness control for each light emission block according to the
content of a displayed image is referred to as local dimming
control.
[0007] On the other hand, when brightness control for each light
emission block is carried out by means of local dimming control,
there will be a problem of unevenness in brightness of the LED
backlight apparatus as a whole. One factor for this problem is that
temperature variation among the light emission blocks is caused by
the brightness control for each light emission block, so that the
brightness of each light emission block varies due to the
temperature characteristics of the LEDs. Another factor is that
variation in the extent of aged deterioration among the light
emission blocks is caused due to the brightness control for each
light emission block, thus resulting in brightness variation.
[0008] As a technique of reducing the brightness unevenness
generated due to such variation in temperature among the light
emission blocks and in the extent of aged deterioration, there is
known a technique of detecting and correcting the brightness of
each light emission block by means of an optical sensor in a state
where the individual light emission blocks are caused to turn on in
a sequential manner.
[0009] In international laid-open publication No. 2008/029548, the
time required to carry out the calibration of an LED backlight
apparatus is made shorter, by detecting the brightnesses of
individual light emission blocks at the same time with the use of a
plurality of optical sensors in a state where the plurality of
light emission blocks, which are arranged at an interval d apart
from each other, are caused to turn on at the same time.
SUMMARY OF THE INVENTION
[0010] In the above-mentioned conventional technique, there has
been a case where the calibration could not be carried out with
sufficient accuracy. That is because detection errors resulting
from the fact that lights emitted from the light emission blocks
which emit the lights at the same time enter each optical sensor as
leakage light may become large, depending on the positional
relationship of each of the plurality of optical sensors and each
of the plurality of light emission blocks which emit the lights at
the same time.
[0011] In particular, when the number of the optical sensors is
smaller with respect to the number of the light emission blocks,
there has been a case where the detection errors as referred to
above become large.
[0012] Accordingly, the present invention is intended to provide a
technique which is capable of suppressing reduction in accuracy of
calibration, in cases where the calibration is carried out, while
causing a plurality of light emission blocks to emit light at the
same time in a lighting apparatus which is composed of a plurality
of light emission blocks, of which the emissions of light can be
controlled independently of one another.
[0013] A first aspect of the present invention resides in a
lighting apparatus which comprises:
[0014] a plurality of light emission block groups composed of a
plurality of light emission blocks, the emissions of light of which
are able to be controlled independently of one another; and
[0015] a detection unit that is provided for each of said light
emission block groups, and detects a light emission characteristic
of each of light emission blocks which belong to the corresponding
light emission block group;
[0016] wherein said plurality of light emission blocks are grouped
in such a manner that sets of light emission blocks are formed,
each one of which is selected from a plurality of different light
emission block groups, with all said light emission blocks being
included in any of the sets;
[0017] an obtaining unit is provided which carries out control on
all the sets in a sequential manner, such that a plurality of light
emission blocks belonging to a same set are caused to emit light at
the same time, and a light emission characteristic of each of those
light emission blocks which are caused to emit light at the same
time is obtained by a detection unit corresponding to a light
emission block group to which each of the light emission blocks
emitting light at the same time belongs; and
[0018] said grouping is decided in such a manner that a minimum
value, in all the sets, of a detection value ratio becomes as large
as possible, wherein the detection value ratio is a ratio between
an amount of light, of the total amount of light which is received
by each of said detection units at the time when the plurality of
light emission blocks belonging to the same set emit light at the
same time, due to an emission of light from a light emission block
belonging to a light emission block group corresponding to each of
said detection units, and an amount of light, of said total amount
of light, due to an emission of light from another light emission
block which emits light simultaneously with said light emission
block.
[0019] A second aspect of the present invention resides in a
lighting apparatus which comprises:
[0020] a plurality of light emission block groups composed of a
plurality of light emission blocks, the emissions of light of which
are able to be controlled independently of one another; and
[0021] a detection unit group that is provided for each of said
light emission block groups, and is composed of a plurality of
detection units for detecting light emission characteristics of
light emission blocks which belong to the corresponding light
emission block group;
[0022] wherein said plurality of light emission blocks are grouped
in such a manner that sets of light emission blocks are formed,
each one of which is selected from a plurality of different light
emission block groups, with all said light emission blocks being
included in any of the sets;
[0023] an obtaining unit is provided which carries out control on
all the sets in a sequential manner, such that a plurality of light
emission blocks belonging to a same set are caused to emit light at
the same time, and a light emission characteristic of each of those
light emission blocks which are caused to emit light at the same
time is obtained by a detection unit which is the nearest to said
light emission block, among a plurality of detection units
belonging to a detection unit group corresponding to a light
emission block group to which each of the light emission blocks
emitting light at the same time belongs; and
[0024] said grouping is decided in such a manner that a minimum
value, in all the sets, of a detection value ratio becomes as large
as possible, wherein the detection value ratio is a ratio between
an amount of light, of a total amount of light which is received by
each of said detection units, at the time when the plurality of
light emission blocks belonging to the same set emit light at the
same time, due to an emission of light from a light emission block
belonging to a light emission block group corresponding to each of
said detection units, and an amount of light, of said total amount
of light, due to an emission of light from another light emission
block which emits light simultaneously with said light emission
block.
[0025] A third aspect of the present invention resides in a
calibration method for a lighting apparatus which includes:
[0026] a plurality of light emission block groups composed of a
plurality of light emission blocks, the emissions of light of which
are able to be controlled independently of one another; and
[0027] a detection unit that is provided for each of said light
emission block groups, and detects a light emission characteristic
of each of light emission blocks which belong to the corresponding
light emission block group;
[0028] wherein said plurality of light emission blocks are grouped
in such a manner that sets of light emission blocks are formed,
each one of which is selected from a plurality of different light
emission block groups, with all said light emission blocks being
included in any of the sets;
[0029] said method comprising:
[0030] an obtaining step to carry out control on all the sets in a
sequential manner, such that a plurality of light emission blocks
belonging to a same set are caused to emit light at the same time,
and a light emission characteristic of each of those light emission
blocks which are caused to emit light at the same time is obtained
by a detection unit corresponding to a light emission block group
to which each of the light emission blocks emitting light at the
same time belongs; and
[0031] a calibration step to correct an amount of light emission of
each light emission block based on a result of a comparison between
a detected value of a light emission characteristic thereof
obtained in said obtaining step and a target value thereof;
[0032] wherein said grouping is decided in such a manner that a
minimum value, in all the sets, of a detection value ratio becomes
as large as possible, wherein the detection value ratio is a ratio
between an amount of light, of the total amount of light which is
received by each of said detection units at the time when the
plurality of light emission blocks belonging to the same set emit
light at the same time, due to an emission of light from a light
emission block belonging to a light emission block group
corresponding to each of said detection units, and an amount of
light, of said total amount of light, due to an emission of light
from another light emission block which emits light simultaneously
with said light emission block.
[0033] A fourth aspect of the present invention resides in a
calibration method for a lighting apparatus which includes:
[0034] a plurality of light emission block groups composed of a
plurality of light emission blocks, the emissions of light of which
are able to be controlled independently of one another; and
[0035] a detection unit group that is provided for each of said
light emission block groups, and is composed of a plurality of
detection units for detecting light emission characteristics of
light emission blocks which belong to the corresponding light
emission block group;
[0036] wherein said plurality of light emission blocks are grouped
in such a manner that sets of light emission blocks are formed,
each one of which is selected from a plurality of different light
emission block groups, with all said light emission blocks being
included in any of the sets;
[0037] said method comprising:
[0038] an obtaining step to carry out control on all the sets in a
sequential manner, such that a plurality of light emission blocks
belonging to a same set are caused to emit light at the same time,
and a light emission characteristic of each of those light emission
blocks which are caused to emit light at the same time is obtained
by a detection unit which is the nearest to said light emission
block, among a plurality of detection units belonging to a
detection unit group corresponding to a light emission block group
to which each of the light emission blocks emitting light at the
same time belongs; and
[0039] a calibration step to correct an amount of light emission of
each light emission block based on a result of a comparison between
a detected value of a light emission characteristic thereof
obtained in said obtaining step and a target value thereof;
[0040] wherein said grouping is decided in such a manner that a
minimum value, in all the sets, of a detection value ratio becomes
as large as possible, wherein the detection value ratio is a ratio
between an amount of light, of a total amount of light which is
received by each of said detection units, at the time when the
plurality of light emission blocks belonging to the same set emit
light at the same time, due to an emission of light from a light
emission block belonging to a light emission block group
corresponding to each of said detection units, and an amount of
light, of said total amount of light, due to an emission of light
from another light emission block which emits light simultaneously
with said light emission block.
[0041] According to the present invention, in a lighting apparatus
composed of a plurality of light emission blocks of which the
emissions of light are able to be controlled independently of one
another, it is possible to suppress reduction in accuracy of
calibration, in cases where the calibration is carried out while
causing a plurality of light emission blocks to emit light at the
same time.
[0042] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIGS. 1A, 1B and 1C are schematic views showing an example
of the construction of a color image display apparatus according to
embodiments of the present invention.
[0044] FIG. 2 is a construction view of an LED backlight apparatus
according to a first embodiment of the present invention.
[0045] FIG. 3 is a block diagram showing an example of a connection
arrangement in the LED backlight apparatus.
[0046] FIG. 4 shows an example of pairs of light emission blocks,
each pair of which are caused to emit light at the same time.
[0047] FIG. 5 shows an example of actually measured values of a
detection value ratio Rv for each pair of light emission blocks
which are caused to emit light at the same time.
[0048] FIG. 6 shows a relation between a distance between each
light emission block and an optical sensor, and an amount of
incident light to the optical sensor.
[0049] FIGS. 7A, 7B and 7C are schematic views showing relations
among a detection value ratio Rv, detection errors, and a
brightness unevenness maximum value.
[0050] FIG. 8 shows an example of a flow chart showing a procedure
to decide pairs of light emission blocks according to a first
embodiment of the present invention.
[0051] FIG. 9 is a view showing an example of light emission block
groups which become candidates for deciding pairs in the first
embodiment of the present invention.
[0052] FIGS. 10A through 10E are views showing examples of pairs of
light emission blocks to be decided, respectively, in the first
embodiment of the present invention.
[0053] FIG. 11 is a view showing an example of pairs of light
emission blocks decided over a plurality of TOWS.
[0054] FIG. 12 is a view showing another example of pairs of light
emission blocks decided over a plurality of rows.
[0055] FIG. 13 is a construction view of an LED backlight apparatus
according to a second embodiment of the present invention.
[0056] FIG. 14 is a view showing an example of pairs of light
emission blocks to be lit or turned on at the same time, and an
order of detection in the second embodiment of the present
invention.
[0057] FIG. 15 shows an example of a flowchart showing a procedure
to decide pairs of light emission blocks according to the second
embodiment of the present invention.
[0058] FIG. 16 is a view showing an example of light emission block
groups which become candidates for deciding pairs in the second
embodiment of the present invention.
[0059] FIGS. 17A through 17D are views showing examples of pairs of
light emission blocks to be decided, respectively, in the second
embodiment of the present invention.
DESCRIPTION OF THE EMBODIMENTS
First Embodiment
[0060] Herein below, reference will be made to a backlight
apparatus according to a first example of the present invention.
This backlight apparatus is a lighting apparatus (a light emitting
device) which is composed of a plurality of light emission blocks,
the emissions of light of which are able to be controlled
independently of one another, and the plurality of light emission
blocks are grouped into a plurality of light emission block groups,
each of which is composed of a plurality of light emission blocks.
Here, note that the present invention is able to be applied to
other lighting apparatus than a backlight apparatus of a liquid
crystal display device. In addition, an image display apparatus
according to the present invention is not limited to a liquid
crystal display device provided with a liquid crystal panel as a
display panel.
[0061] FIG. 1A is a schematic view showing an example of the
construction of a color image display apparatus, to which the
present invention can be applied. The color image display apparatus
has an LED backlight apparatus 101, a diffuser 102, a condensing
sheet 103, a reflection type polarization film 104, and a color
liquid crystal panel 105.
[0062] The LED backlight apparatus 101 is a backlight apparatus
which irradiates a white light to a back face of the color liquid
crystal panel 105. The LED backlight apparatus 101 has a plurality
of LEDs (Light Emitting Diodes) which are point light sources. The
diffuser 102 serves to operate the LED backlight apparatus 101 as a
surface light source by diffusing light from the above-mentioned
plurality of LEDs. The condensing sheet 103 improves the front
brightness (luminance) of the color liquid crystal panel 105 by
causing white light, which is diffused by the diffuser 102 and is
incident thereto at various angles of incidence, to condense in a
front direction (to a side of the color liquid crystal panel 105).
The reflection type polarization film 104 improves the brightness
displayed on the color liquid crystal panel 105 by polarizing the
incident white light in an efficient manner. The color liquid
crystal panel 105 displays a color image thereon by adjusting the
transmittance of the irradiated white light for each pixel of
RGB.
[0063] FIG. 1B is a schematic view showing an example of the
construction of the LED backlight apparatus 101. The LED backlight
apparatus 101 is constructed of a plurality of LED boards 110 which
are arranged in a matrix form.
[0064] FIG. 1C is a schematic view showing an example of the
construction of an LED board 110. The LED board 110 is composed of
a total of eight (2.times.4) light emission blocks 111. Each light
emission block 111 has four LED chips 112 which are arranged at
equal intervals. The individual LED chips 112 are electrically
connected in series to one another, so that brightness (intensity)
control can be made for each light emission block 111 as one
control unit. Each LED chip 112 may be composed of a white LED, or
may instead be constructed by a combination of LEDs of multiple
colors such as RGB (red, green and blue) which are combined so as
to emit white color light.
[0065] Mounted on each LED board 110 is an optical sensor 113 which
acts as a photodetection unit for detecting the light emission
(luminescence) characteristics of the corresponding light emission
blocks 111. As the optical sensor 113, there is used a sensor which
is able to measure a change in the amount of light (brightness),
such as a photo diode, a photo transistor, etc. In addition, as an
optical sensor, there may be used a sensor which is able to detect
at least either of brightness and chromaticity. Light emitted from
each light emission block 111 enters a corresponding optical sensor
113, after being reflected by the diffuser 102 or the reflection
type polarization film 104, so that a brightness change in each
light emission block 111 is detected.
[0066] With the construction of this embodiment, there is one
optical sensor with respect to eight light emission blocks 111. In
order to suppress or reduce the cost and the circuit size, it is
desirable that the number of optical sensors be small in this
manner.
[0067] FIG. 2 is a schematic view showing an example of the
arrangement of the LED boards 110, the light emission blocks 111
and the optical sensors 113 in the LED backlight apparatus 101,
when seen from a front direction (i.e., from a side of the color
liquid crystal panel 105). An LED board 110 (1, 1) is arranged at
an upper left end of the LED backlight apparatus 101, and an LED
board 110 (1, 2) is arranged in a lateral or horizontal right
direction of the LED board 110 (1, 1), and an LED board 110 (2, 1)
and an LED board 110 (3, 1) are arranged in order in a longitudinal
Or vertical downward direction. Similarly, an LED board 110 (2, 2)
and an LED board 110 (3, 2) are arranged in order in a longitudinal
or vertical downward direction of the LED board 110 (1, 2) which is
at an upper right side of the LED backlight apparatus 101. As
mentioned above, the LED backlight apparatus 101 is constructed of
a total of six LED boards 110, which are arranged in a 2.times.3
matrix form (i.e., 2 columns (in the horizontal direction) by 3
rows (in the vertical direction)).
[0068] The LED board 110 (1, 1) is composed of a light emission
block 111 (1, 1, 1), a light emission block 111 (1, 1, 2), a light
emission block 111 (1, 1, 3), a light emission block 111 (1, 1, 4),
a light emission block 111 (1, 1, 5), a light emission block 111
(1, 1, 6), a light emission block 111 (1, 1, 7), a light emission
block 111 (1, 1, 8), and an optical sensor 113 (1, 1). Each of the
other LED boards 110 (1, 2), 110 (2, 1), 110 (2, 2), 110 (3, 1),
110 (3, 2) has the same construction as that of the LED board 110
(1, 1) (refer to FIG. 2).
[0069] FIG. 3 is a block diagram showing an example of a connection
arrangement in the LED backlight apparatus 101. The internal
configurations of a total of six sheets of LED boards 110 are
equivalent to one another, and so the LED board 110 (1, 1) will be
explained, as an example. The LED board 110 (1, 1) is provided with
the light emission block 111 (1, 1, 1) through the light emission
block 111 (1, 1, 8). The brightnesses (intensities) of the
individual light emission blocks 111 (1, 1, 1) through 111 (1, 1,
8) are controlled by means of PWM control from an LED driver 120
(1, 1, 1) through an LED driver 120 (1, 1, 8), respectively. Here,
note that a method of brightness control may be based on an amount
of electric current or voltage. Most of a light emission 121 (1, 1,
1) through a light emission 121 (1, 1, 8) from the individual light
emission blocks 111 (1, 1, 1) through 111 (1, 1, 8), respectively,
are incident to the color liquid crystal panel 105 (not shown in
FIG. 3). However, a part of these light emissions is incident to
the optical sensor 113 (1, 1) after being reflected by the diffuser
102 (not shown in FIG. 3) or by the reflection type polarization
film 104 (not shown in FIG. 3).
[0070] In order to reduce brightness unevenness generated due to
variations in the temperature and the extent of aged deterioration
among the light emission blocks 111, the brightnesses of the light
emission blocks 111 are detected by the use of the optical sensors
113 at periodical or specific timing.
[0071] The brightness detection by the optical sensor 113 (1, 1) is
carried out in a state where any one of the light emission block
111 (1, 1, 1) through the light emission block 111 (1, 1, 8) is lit
or turned on. According to this, the brightness detection is made
possible in a state where a light emission 121 from any one of the
light emission 121 (1, 1, 1) through the light emission 121 (1, 1,
8) has entered the optical sensor 113 (1, 1). In this connection,
however, leakage light (not shown in FIG. 3) from light emission
blocks 111 of other LED boards 110 which have been turned on at the
same time also enters the optical sensor 113 (1, 1). In this
embodiment, in a state where a plurality of light emission blocks
111 belonging to different LED boards 110, respectively, are caused
to turn on at the same time, brightnesses are detected by the use
of a plurality of optical sensors 113 which similarly belong to the
different LED boards 110, respectively. This shortens the time
required for detection and correction of the LED backlight
apparatus 101 as a whole.
[0072] An analog value 122 (1, 1) of an optical sensor detection
brightness outputted from the optical sensor 113 (1, 1) is
subjected to an analog to digital conversion by an A/D converter
123 (1, 1), and a digital value 124 (1, 1) of the optical sensor
detection brightness thus obtained is inputted to a microcomputer
125.
[0073] Similarly, analog values 122 of optical sensor detection
brightnesses from the other LED boards 110 are also subjected to
analog to digital conversion by means of corresponding A/D
converters 123, respectively, and digital values 124 of the optical
sensor detection brightnesses of a total of six channels are
inputted to the microcomputer 125.
[0074] A brightness target value of each light emission block 111,
which has been decided at the time of manufacturing test of the
color image display apparatus, etc., is held in a non-volatile
memory 126 which is connected to the microcomputer 125. By causing
each light emission block 111 to emit light at a brightness
equivalent to its target brightness value, the brightness
unevenness of the LED backlight apparatus as a whole is
suppressed.
[0075] In the microcomputer 125, the brightness of each light
emission block 111 is obtained after subtracting a detection
brightness due to the influence of leakage light from a digital
value 124 of a corresponding optical sensor detection
brightness.
[0076] In the microcomputer 125, a comparison is made between the
brightness of each light emission block 111 and a target brightness
value of the light emission block 111 held in the non-volatile
memory 126, and a corresponding LED driver 120 is controlled so
that the brightness of each light emission block 111 becomes
equivalent to its target brightness value. The control of each LED
driver 120 is carried out through a corresponding LED driver
control signal 127 from the microcomputer 125.
[0077] In this embodiment, the microcomputer 125 causes a total of
two light emission blocks 111 selected one by one from different
LED boards 110 to emit light in one set at the same time, and
obtains the values of brightnesses detected at that time by optical
sensors 113 which are provided on LED boards 110 to which the two
light emission blocks 111 belong, respectively. Although each
optical sensor 113 has, for its brightness detection objects, those
light emission blocks 111 which belong to an LED board 110 on which
the optical sensor 113 is provided, the light emitted by the other
light emission block 111 which carries out simultaneous light
emission with the one light emission block 111 enters other optical
sensors 113 as a leakage light. An error is contained in the
detection value of the brightness of a light emission block 111
detected by each optical sensor 113, resulting from this leakage
light. The microcomputer 125 corrects the error contained in the
detection value of the brightness detected by each optical sensor
113, and carries out calibration to correct an amount of light
emission (PWM control value, etc.) of each light emission block 111
based on the result of a comparison between the detection value
thus corrected and a corresponding target value stored in the
non-volatile memory 126. As the number of light emission blocks
increases, the time required for calibration becomes longer.
However, by causing a plurality of light emission blocks to emit
light at the same time and carrying out the calibration of the
plurality of light emission blocks at the same time in this manner,
it is possible to shorten the time required for the calibration of
the entire backlight apparatus. Although in this embodiment, an
example is described in which two light emission blocks are caused
to emit light at the same time to carry out the calibration
thereof, the number of light emission blocks which are caused to
emit light at the same time is not limited to this. In addition,
data with respect to the influence and error which are exerted on
the detected values of the optical sensors 113 by the leakage
lights from the light emission blocks 111 carrying out simultaneous
light emissions have been investigated and stored in the
non-volatile memory 126 in advance. The microcomputer 125 can
correct the error by referring to this data. Alternatively, the
construction may also be such that the relation between the
positional relation of the light emission blocks 111 carrying out
simultaneous light emissions and each optical sensor 113, and the
influence exerted on the detected values of the optical sensors 113
by the leakage lights is obtained by arithmetic operations.
[0078] FIG. 4 is a correspondence table showing an example of the
order of detection of the individual light emission blocks 111 and
grouping or combination of light emission blocks 111 which are
caused to turn on at the same time at each turn of detection.
Brightness detection of the individual light emission blocks 111 is
carried out according to the order of detection 200 for all the
sets or pairs in a sequential manner. The order of detection 200 is
decided from the 1st to the 24th, and at each turn of the order of
detection 200, two light emission blocks 111 are caused to emit
light at the same time. That is, they are a light emission block
A201 selected from a light emission block group A which is a first
light emission block group, and a light emission block B203
selected from a light emission block group B which is a second
light emission block group. In addition, each brightness detection
is carried out by the use of an optical sensor 202 for detection of
the light emission blocks A which is a first detection unit
corresponding to the first light emission block group, and an
optical sensor 204 for detection of the light emission blocks B
which is a second detection unit corresponding to the second light
emission block group.
[0079] Here, when seen from a front direction (from the side of the
color liquid crystal panel 105), a left half of the LED backlight
apparatus 101 is assigned as light emission blocks A201, and a
right half thereof is assigned as light emission blocks B203.
[0080] For example, in the first of the order of detection 200, a
total of two light emission blocks 111, i.e., the light emission
block 111 (1, 1, 1) as a light emission block A201 and the light
emission block 111 (1, 2, 4) as a light emission block B203, are
caused to turn on at the same time. In addition, brightness
detection is carried out by using the optical sensor 113 (1, 1) as
an optical sensor 202 for detection of the light emission blocks A,
and the optical sensor 113 (1, 2) as an optical sensor 204 for
detection of the light emission blocks B, respectively.
[0081] The set or combination of a light emission block A201 and a
light emission block B203, which are caused to turn on at the same
time at each turn of the order of detection 200, is decided in such
a manner that a minimum value of a detection value ratio Rv of each
light emission block 111 in the entire backlight apparatus 101
becomes more larger. A decision procedure for such a combination
will be described later in detail. In addition, details will also
be described later for the definition of the detection value ratio
Rv and the reason for using such a combination in which the minimum
value of the detection value ratio Rv of each light emission block
111 in the entire backlight apparatus becomes larger. The
information on the pairs of the light emission blocks to be caused
to emit light at the same time and the order of detection as shown
in FIG. 4 has been set in advance and stored in the non-volatile
memory 126. By referring to table data of FIG. 4 at the time of
execution of calibration, the microcomputer 125 obtains the
information on a combination of light emission blocks to be caused
to emit light at the same time and an order of detection thereof.
Then, the LED drivers 120 are controlled by the microcomputer 125
so that two light emission blocks in combination thus obtained are
caused to emit light at the same time according to the order of
detection thus obtained. Thereafter, the microcomputer 125 carries
out calibration of the backlight apparatus by obtaining the
detected value of an optical sensor 113 at that time, and making a
comparison of the detected value with a target value thereof.
[0082] FIG. 5 is a correspondence table showing an example of a
measured value of the detection value ratio Rv in each light
emission block 111 at each turn in the order of detection 200 shown
in the correspondence table of FIG. 4. With respect to each of a
light emission block A201 and a light emission block B203 at each
turn in the order of detection 200, a detection value ratio R.sub.V
205 for the light emission block A and a detection value ratio
R.sub.V206 for the light emission block B are obtained by actual
measurements. It can be seen from the correspondence table of FIG.
5 that the minimum value of the detection value ratio R.sub.V of
each light emission block 111 in the entire backlight apparatus in
this embodiment is 2.1.
[0083] In the following, the definition of the detection value
ratio R.sub.V will be described.
[0084] FIG. 6 is a graph in which an amount of incident light (y)
to an optical sensor 113 at the time of causing one certain light
emission block 111 to turn on independently is plotted with respect
to a distance (x) between the light emission block and the optical
sensor 113. Light emitted from the light emission block 111 enters
the optical sensor 113, after being reflected by the diffuser 102
and the reflection type polarization film 104, which are arranged
directly above the optical sensor 113. For that reason, a curve
(y=f.sub.v (x)) is drawn in which the amount of incident light (y)
to the optical sensor becomes larger in inverse proportion to the
decreasing distance (x) between the light emission block and the
optical sensor. In other words, the nearer the light emission block
111 and the optical sensor 113, the more becomes the amount of
incident light to the optical sensor 113.
[0085] The detection value ratio R.sub.V is a ratio of a detected
value of an amount of light due to the emission of light 121 from
one light emission block 111 to be detected, and a detected value
of an amount of light due to leakage light from the other light
emission block 111 which is turned on at the same time, in the
detected value of the amount of light received by one certain
optical sensor 113 (the following expression 1).
Rv = detection value due to an emission of light from a light
emission block to be detected detection value due to leakage light
from another light emission block being turned on at same time (
Expression 1 ) ##EQU00001##
[0086] The numerator and the denominator of the expression 1 are
both in inverse proportion to the distance between the light
emissions block 111 and the optical sensor 113, as shown in FIG. 6.
Accordingly, it can be said that in one certain optical sensor 113,
the detection value ratio R.sub.V is also in inverse proportion to
the distance between the one light emission block 111 to be
detected and the optical sensor 113 divided by the distance between
the other light emission block 111 being turned on at the same time
and the optical sensor 113 (the following expression 2).
1 Rv .varies. distance between light emission block to be detected
and optical sensor distance between another light emission block
being turned on at the same time and optical sensor ( Expression 2
) ##EQU00002##
[0087] From the above, it can be seen that in order to make the
detection value ratio R.sub.V larger, the distance between the one
light emission block 111 to be detected and the optical sensor 113
should be made smaller, and the distance between the other light
emission block 111 being turned on at the same time and the optical
sensor 113 should be made larger.
[0088] Next, reference will be made to the reason for using such a
combination in which the minimum value of the detection value ratio
R.sub.V of each light emission block 111 in the entire backlight
apparatus becomes larger.
[0089] FIG. 7A is a schematic diagram showing an example of
components of an optical sensor detection brightness in cases where
the detection value ratio R.sub.V is large. An optical sensor
detection brightness 302a has its components including, as a major
proportion, a detection brightness 300a due to the emission of
light from the light emission block 111 which becomes an object to
be detected, and as a small proportion, a detection brightness 301a
due to leakage light from the other light emission block 111 being
turned on at the same time.
[0090] FIG. 7B is a schematic diagram showing an example of
components of an optical sensor detection brightness in cases where
the detection value ratio R.sub.V is small. An optical sensor
detection brightness 302b has its components divided into two
nearly equal proportions, i.e., a detection brightness 300b due to
the emission of light from the light emission block 111 which
becomes an object to be detected, and a detection brightness 301b
due to leakage light from the other light emission block 111 being
turned on at the same time.
[0091] The optical sensor detection brightness 302a in FIG. 7A and
the optical sensor detection brightness 302b in FIG. 7B are gain
controlled in such a manner that their digital values obtained
after these detection brightnesses are subjected to analog to
digital conversion by means of the A/D converters 123 become
equivalent to each other. Accordingly, in cases where the detection
value ratio R.sub.V is small, as shown in FIG. 7B, the digital
value of the detected brightness 300b after analog to digital
conversion thereof due to the emission of light from the light
emission block 111 to be detected will also be small. In other
words, in cases where the detection value ratio R.sub.V is small, a
detection error due to a quantum error or the like becomes
large.
[0092] FIG. 7C is a schematic diagram showing the relation between
detection errors of the individual light emission blocks 111 of the
entire backlight apparatus, and a maximum value of the brightness
unevenness of the backlight apparatus. As explained before, a
detection error 400 of each light emission block is decided
according to the detection value ratio Rv of the light emission
block 111. A maximum value 401 of the brightness unevenness of the
backlight apparatus is decided by a maximum value of the detection
error 400 of each light emission block in the entire backlight
apparatus. Accordingly, it can be seen that the brightness
unevenness maximum value 401 of the backlight apparatus can be
suppressed by using a combination in which a minimum value of the
detection value ratio R.sub.V in the entire backlight apparatus
becomes larger.
[0093] Next, reference will be made to a procedure for deciding
such a combination in which the minimum value of the detection
value ratio R.sub.V of each light emission block 111 in the entire
backlight apparatus becomes larger.
[0094] FIG. 8 is an example of a flow chart showing a procedure to
decide combinations (pairs) of light emission blocks. The
processing shown in this flow chart is carried out by a computer
which is different or separate from the backlight apparatus, for
example at the time of production of the backlight apparatus, and
table data, as shown in FIG. 4, obtained as a result of the
execution is written into the non-volatile memory 126 of the
backlight apparatus. As a result of this, the microcomputer 125 can
carry out the calibration of the backlight apparatus in the order
of detection and the combination of the light emission blocks 111
according to this table data. Alternatively, it may be constructed
such that a program to cause the microcomputer 125 to carry out the
processing represented by this flow chart has been stored in the
non-volatile memory 126, and table data as shown in FIG. 4 is
created by the microcomputer 125 by causing the microcomputer 125
to execute the program. Alternatively, the construction may be such
that a program represented by this flow chart is provided to the
backlight apparatus or the liquid crystal display device through a
cable or radio communication means or a recording medium such as a
memory card, a CD-ROM, or the like, whereby the program thus
provided is executed by the microcomputer 125. Alternatively, a
computer, on which a program represented by this flow chart is
installed and which is connected to the liquid crystal display
device through a cable or radio communication means, may obtain
configuration information on the light emission blocks 111 of the
backlight apparatus, etc., through the communication means. Then,
the computer may create table data as shown in FIG. 4 by carrying
out the processing of this flow chart based on the configuration
information thus obtained. In this case, the computer may have a
function to control the backlight apparatus of the liquid crystal
display device from the outside thereof based on the table data
thus created, or may transmit the created table data to the liquid
crystal display device so that the microcomputer 125 can refer to
the table data. In addition, a backlight apparatus, which carries
out calibration by the use of the table data shown in FIG. 4, and
its calibration method, are included in the scope of the present
invention, without regard to a main body or component to execute
the decision procedure represented by this flow chart. First, in
step S101, groups of light emission blocks 111 which become
candidates at the time of deciding pairs are selected from groups
of light emission blocks A201 and groups of light emission blocks
B203.
[0095] FIG. 9 is a schematic view showing an example of groups of
light emission blocks 111 which have been selected in step S101. In
this embodiment, when looking at the LED backlight apparatus 101
from its front direction (from the side of the color liquid crystal
panel 105), groups of light emission blocks lying in the left half
thereof are assigned as the groups of light emission blocks A201,
and groups of light emission blocks lying in the right half thereof
are assigned as the groups of light emission blocks B203. From
among these, light emission blocks 111 at the first row from the
upper end are selected as groups of light emission blocks 111 which
become candidates at the time of deciding pairs. Specifically, four
of the light emission block 111 (1, 1, 1) through the light
emission block 111 (1, 1, 4) are selected from the groups of light
emission blocks A201, and four of the light emission block 111 (1,
2, 1) through the light emission block 111 (1, 2, 4) are selected
from the groups of light emission blocks B203. Here, the reason for
having selected the groups of light emission blocks 111 at one row
as candidates will be explained below. That is, it may be
constructed such that in lighting control by means of the PWM of
the backlight apparatus, light emission blocks 111 at the same row
are controlled to be turned on in synchronization in timing with
one another. This is because in this case, it is easy to carry out
control to cause a plurality of light emission blocks 111 to be
turned on at the same time, in the case of brightness detection.
However, how to select groups of light emission blocks which become
candidates at the time of deciding pairs is not limited to the
above-mentioned example. As will be described later, it is also
permitted to make such a selection that four light emission blocks
111 to be selected from the groups of light emission blocks A201,
and four light emission blocks 111 to be selected from the groups
of light emission blocks B203 belong to different rows,
respectively.
[0096] Then, in step S102 in FIG. 8, in those groups of light
emission blocks 111 in which pairing has not yet been made, among
the groups of light emission blocks 111 selected in step S101, (1)
a light emission block 111 in a group of light emission blocks
A201, which is the nearest to an optical sensor 113 for detection
of a group of light emission blocks B203, and (2) a light emission
block 111 in the group of light emission blocks B203, which is the
nearest to the optical sensor 113 for detection of the group of
light emission blocks B203, are decided as a pair.
[0097] FIG. 10A is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S102.
The light emission block 111 (1, 1, 4) is selected as "a light
emission block 111 in a group of light emission blocks A201, which
is the nearest to an optical sensor 113 for detection of a group of
light emission blocks B203". In addition, the light emission block
111 (1, 2, 3) is selected as "a light emission block 111 in the
group of light emission blocks B203, which is the nearest to the
optical sensor 113 for detection of the group of light emission
blocks B203". As the latter (i.e., the light emission block 111 in
the group of light emission blocks B203), the light emission block
111 (1, 2, 2) may instead be selected.
[0098] FIG. 10B is a schematic view showing a state of light
emission at the time when the light emission blocks 111 (1, 1, 4)
and 111 (1, 2, 3) decided as a pair in step S102 have been turned
on at the same time. The light emission block 111 (1, 1, 4) and the
optical sensor 113 (1, 1) for detecting this are separated from
each other by 2 blocks, so the amount of incident light to the
optical sensor 113 (1, 1) by the emission of light 130 (1, 1, 4)
from the light emission block 111 (1, 1, 4) is not so large.
However, the light emission block 111 (1, 2, 3) being turned on at
the same time and the optical sensor 113 (1, 1) are separated from
each other by 5 blocks, so the amount of incident light to the
optical sensor 113 (1, 1) by leakage light 131 (1, 2, 3) from the
light emission block 111 (1, 2, 3) is small to a sufficient extent.
Accordingly, a sufficiently large value is obtained for the
detection value ratio R.sub.V of the light emission block 111 (1,
1, 4). As previously shown in FIG. 5, the measured value of the
detection value ratio R.sub.V of the light emission block 111 (1,
1, 4) is 6.6. Here, for example, if the light emission block 111
(1, 1, 4) and the light emission block 111 (1, 2, 1) are decided as
a pair, without following the combination decision procedure of
this embodiment, the detection value ratio R.sub.V of the light
emission block 111 (1, 1, 4) will become remarkably small.
[0099] On the other hand, the light emission block 111 (1, 1, 4)
and the optical sensor 113 (1, 2) are separated from each other by
only 3 blocks, so the amount of incident light to the optical
sensor 113 (1, 2) by leakage light 131 (1, 1, 4) from the light
emission block 111 (1, 1, 4) is relatively large. However, the
light emission block 111 (1, 2, 3) and the optical sensor 113 (1,
2) for detecting this are also separated from each other by only 1
block, so the amount of incident light to the optical sensor 113
(1, 2) by the emission of light 130 (1, 2, 3) from the light
emission block 111 (1, 2, 3) is large to a sufficient extent.
Accordingly, a not so small value is obtained for the detection
value ratio R.sub.V of the light emission block 111 (1, 2, 3). As
previously shown in FIG. 5, the measured value of the detection
value ratio R.sub.V of the light emission block 111 (1, 2, 3) is
2.1. Here, for example, if the light emission block 111 (1, 1, 4)
and the light emission block 111 (1, 2, 4) are decided as a pair,
without following the combination decision procedure of this
embodiment, the detection value ratio R.sub.V of the light emission
block 111 (1, 1, 4) will become remarkably small.
[0100] Returning to FIG. 8, in step S103, in those groups of light
emission blocks 111 in which pairing has not yet been made, among
the groups of light emission blocks 111 selected in step S101, (1)
a light emission block 111 in the group of light emission blocks
B203, which is the nearest to the optical sensor 113 for detection
of the group of light emission blocks A201, and (2) a light
emission block 111 in the group of light emission blocks A201,
which is the nearest to the optical sensor 113 for detection of the
group of light emission blocks A201, are decided as a pair.
[0101] FIG. 10C is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S103.
The light emission block 111 (1, 2, 1) is selected as "a light
emission block 111 in the group of light emission blocks B203,
which is the nearest to the optical sensor 113 for detection of the
group of light emission blocks A201". In addition, the light
emission block 111 (1, 1, 2) is selected as "a light emission block
111 in the group of light emission blocks A201, which is the
nearest to the optical sensor 113 for detection of the group of
light emission blocks A201". As the latter (i.e., the light
emission block 111 in the group of light emission blocks A201), the
light emission block 111 (1, 1, 3) may instead be selected.
[0102] Thereafter, in step S104 of FIG. 8, it is determined whether
all the pairs of the light emission blocks 111 which become
candidates have been decided. In cases where all the pairs of the
light emission blocks 111 which become candidates have been
decided, the procedure of this flow chart is all completed, but in
cases where they have not yet been decided, a return is again made
to step S102.
[0103] FIG. 10D is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S102
of a second round. The light emission block 111 (1, 1, 3) is
selected as "a light emission block 111 in the group of light
emission blocks A201, which is the nearest to the optical sensor
113 for detection of the group of light emission blocks B203". In
addition, the light emission block 111 (1, 2, 2) is selected as "a
light emission block 111 in the group of light emission blocks
B203, which is the nearest to the optical sensor 113 for detection
of the group of light emission blocks B203".
[0104] FIG. 10E is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S103
of the second round. Here, there is only one light emission block
111 which has not yet been decided as a pair, in each of the group
of light emission blocks A201 and the group of light emission
blocks B203, and hence, there is no combination which makes a pair,
other than a combination of the light emission block 111 (1, 1, 1)
and the light emission block 111 (1, 2, 4).
[0105] From the above, it means that the 1st to the 4th of the
order of detection 200 in the correspondence table of FIG. 4 have
been decided by the combination decision procedure shown in FIG. 8.
With reference to the 5th to the 24th of the order of detection
200, it is possible to decide them by selecting, in step S101 of
FIG. 8, light emission blocks 111 from the second row onward from
the upper end as groups of light emission blocks 111 which become
candidates at the time of deciding pairs.
[0106] Here, reference has been made to an example in which in step
S101 of FIG. 8, groups of light emission blocks 111 at one row are
selected as groups of light emission blocks 111 which become
candidates at the time of deciding pairs. However, it is also
possible to decide pairs from among groups of light emission blocks
111 over a plurality of rows according to the above-mentioned pair
decision method.
[0107] FIG. 11 is a schematic view showing an example of a pair
decided among from groups of light emission blocks 111 over a
plurality of rows. In the example of FIG. 11, the light emission
block 111 (1, 1, 1) through the light emission block 111 (1, 1, 4)
are selected as a group of light emission blocks A201, and the
light emission block 111 (2, 2, 1) through the light emission block
111 (2, 2, 4) are selected as a group of light emission blocks
B203. The example of FIG. 11 is an example of a combination of
light emission blocks 111 which are decided as a pair in step S102
of a first round, in cases where the pair is decided according to
the flow chart of FIG. 8. The light emission block 111 (1, 1, 4) is
selected as a light emission block A201, and the light emission
block 111 (2, 2, 3) is selected as a light emission block B203.
Thus, in cases where four light emission blocks at the 1st row of
the LED board 110 (1, 1) and four light emission blocks at the 1st
row of the LED board 110 (2, 2) are selected as candidates for pair
decision, too, a pair can be decided according to the flow chart of
FIG. 8. Here, note that the pair shown in FIG. 11 is resultantly
equal to one in the 4th of the order of detection 200 in the
correspondence table of FIG. 4 in which the light emission block
111 (1, 2, 3) paired with the light emission block 111 (1, 1, 4) is
replaced by the light emission block 111 (2, 2, 3) which is away
therefrom by two rows. Similarly, light emission blocks 111 in the
light emission blocks B203 in the correspondence table of FIG. 4
are replaced by light emission blocks 111 away therefrom by two
rows, respectively. According to this, it becomes possible to
obtain the pairs which are decided in cases where four light
emission blocks at the 1st row of the LED board 110 (1, 1) and four
light emission blocks at the 1st row of the LED board 110 (2, 2)
are selected as candidates for pair decision.
[0108] FIG. 12 is a schematic view showing an example of an
arrangement of pairs decided from among groups of light emission
blocks 111 over a plurality of rows. The numbers in this figure are
values which correspond to the order of detection 200, and light
emission blocks 111 of the same values form pairs. The pair of the
light emission block 111 (1, 1, 4) and the light emission block 111
(2, 2, 3) exemplified in FIG. 11 is an example in which the group
of light emission blocks A201 and the group of light emission
blocks B203 are away from each other by two rows. On the other
hand, for example, in pairs of the 17th--the 20th of the order of
detection shown in FIG. 12, a group of light emission blocks A201
and a group of light emission blocks B203 are away from each other
by four rows. In this manner, even in cases where groups of light
emission blocks 111 which become candidates for deciding pairs,
i.e., a group of light emission blocks A201 and a group of light
emission blocks B203, are away from each other by a plurality of
rows, pairs can be decided according to the flow chart of FIG.
8.
[0109] As described above, by applying this embodiment, the
brightnesses of a plurality of light emission blocks 111 are
detected at the same time by the use of a plurality of optical
sensors 113 in a state where the plurality of light emission blocks
111 are caused to turn on at the same time. Then, at that time,
detection errors will occur because lights emitted by light
emission blocks 111 other than a light emission block 111 which is
to be detected by a corresponding optical sensor 113 enter each
optical sensor 113 as leakage light. However, it is possible to
carry out calibration by causing a plurality of light emission
blocks 111 to emit light at the same time in a combination thereof
which can make such detection errors as small as possible. Thus,
when calibration is carried out based on the result of detection in
which the brightnesses of a plurality of light emission blocks are
detected at the same time by a plurality of optical sensors
corresponding to the individual light emission blocks,
respectively, by causing the plurality of light emission blocks to
emit light at the same time, in a combination thereof decided by
the method explained in this embodiment, it is possible to carry
out the calibration with a high degree of accuracy. As a result,
according to this embodiment, it becomes possible to suppress
brightness unevenness in an effective manner.
[0110] Incidentally, another method can also be considered in which
combinations are all decided from the detection value ratio R.sub.V
according to actual measurements, without using the combination
decision procedure shown in FIG. 8 of this embodiment. In this
case, however, it is necessary to make actual measurements covering
examples of all combinations or sets, and hence such a method is
not efficient, and the predominance of using the combination
decision procedure of this embodiment is high.
Second Embodiment
[0111] In this second embodiment, reference will be made to the
fact that the present invention can be applied, even in cases where
the number of optical sensors with respect to the number of the
light emission blocks is different from that in the first
embodiment. Here, note that in the individual figures and
procedures, the same parts or elements as those of the
above-mentioned first embodiment are denoted by the same reference
numerals and characters, and the explanation thereof is omitted.
Hereinafter, a backlight apparatus according to the second
embodiment of the present invention will be described.
[0112] FIG. 13 is a schematic view showing an example of the
arrangement of LED boards 110, light emission blocks 111 and
optical sensors 113 in an LED backlight apparatus 101, when seen
from a front direction (i.e., from a side of a color liquid crystal
panel 105). An LED board 110 (1, 1) is arranged at an upper left
end of the LED backlight apparatus 101, and an LED board 110 (1,
2), an LED board 110 (1, 3) and an LED board 110 (1, 4) are
arranged in order in a lateral or horizontal right direction of the
LED board 110 (1, 1). In addition, an LED board 110 (2, 1) and an
LED board 110 (3, 1) are arranged in order in a longitudinal or
vertical downward direction of the LED board 110 (1, 1). Similarly,
an LED board 110 (2, 2) and an LED board 110 (3, 2) are arranged in
order in a longitudinal or vertical downward direction of the LED
board 110 (1, 2); an LED board 110 (2, 3) and an LED board 110 (3,
3) are arranged in order in a longitudinal or vertical downward
direction of the LED board 110 (1, 3); and an LED board 110 (2, 4)
and an LED board 110 (3, 4) are arranged in order in a longitudinal
or vertical downward direction of the LED board 110 (1, 4). As
mentioned above, the LED backlight apparatus 101 of this second
embodiment is constructed of a total of twelve LED boards 110,
which are arranged in a 4.times.3 matrix form (i.e., 4 columns (in
the horizontal direction) by 3 rows (in the vertical
direction)).
[0113] The LED board 110 (1, 1) is composed of a light emission
block 111 (1, 1, 1), a light emission block 111 (1, 1, 2), a light
emission block 111 (1, 1, 3), a light emission block 111 (1, 1, 4),
and an optical sensor 113 (1, 1). Each of the other LED boards 110
(1, 2) through 110 (1, 4), 110 (2, 1) through 110 (2, 4), 110 (3,
1) through 110 (3, 4) and 110 (4, 1) through 110 (4, 4) has the
same construction as that of the LED board 110 (1, 1) (refer to
FIG. 13).
[0114] FIG. 14 is a correspondence table showing an example of the
order of detection of the individual light emission blocks 111 and
grouping or combination of light emission blocks 111 which are
caused to turn on at the same time at each turn of detection.
Brightness detection of the individual light emission blocks 111 is
carried out according to the order of detection 500. The order of
detection 500 is decided from the 1st to the 24th, and at each turn
of the order of detection 500, a total of two light emission blocks
111 including a light emission block A501 and a light emission
block B503 are caused to turn on at the same time. In addition,
brightness detection of the light emission blocks 111 is carried
out by the use of an optical sensor 502 for detection of light
emission blocks A, and an optical sensor 504 for detection of light
emission blocks B. That is, an optical sensor 502 for detection of
light emission blocks A detects, as objects to be detected, light
emission blocks 111 of a group of light emission blocks A501, and
an optical sensor 504 for detection of light emission blocks B
detects, as objects to be detected, light emission blocks 111 of a
group of light emission blocks B503. An optical sensor 113 which is
provided on an LED board 110 to which light emission blocks 111
belong is an optical sensor 113 which detects those light emission
blocks 111 as objects to be detected. That is, an optical sensor
113 (L, M) detects light emission blocks 111 (L, M, K) as objects
to be detected (here, L=1-3, M=1-4, K=1-4). However, detection
errors will occur because lights emitted from light emission blocks
111 other than alight emission block 111 which is assumed to be
detected by a corresponding optical sensor 113 enter each optical
sensor 113 as leakage light. Such a situation is the same as that
in the above-mentioned first embodiment. A method of deciding a
pair of light emission blocks 111 which are caused to emit light at
the same time so as to make such detection errors small will be
explained hereinafter.
[0115] Here, groups of light emission blocks, which are arranged in
the left half of the LED backlight apparatus 101 when seen from a
front direction (from the side of the color liquid crystal panel
105), are assigned as groups of light emission blocks A501, which
are a first light emission block group. In addition, groups of
light emission blocks, which are arranged in the right half of the
LED backlight apparatus 101, are assigned as groups of light
emission blocks B503, which are a second light emission block
group.
[0116] For example, in the first of the order of detection 500, a
total of two light emission blocks 111, i.e., the light emission
block 111 (1, 1, 1) as a light emission block A501 and the light
emission block 111 (1, 3, 2) as a light emission block B503, are
caused to turn on at the same time. In addition, brightness
detection is carried out by using the optical sensor 113 (1, 1) as
an optical sensor 502 for detection of light emission blocks A, and
the optical sensor 113 (1, 3) as an optical sensor 504 for
detection of light emission blocks B, respectively.
[0117] The set or combination of a light emission block A501 and a
light emission block B503, which are caused to turn on at the same
time at each turn of the order of detection 500, is decided in such
a manner that a minimum value of a detection value ratio Rv of each
light emission block 111 in the entire backlight apparatus 101
becomes more larger. A decision procedure for such a combination
will be described hereafter.
[0118] FIG. 15 is an example of a flow chart showing a procedure to
decide combinations (pairs) of light emission blocks. First, in
step S501, groups of light emission blocks 111 which become
candidates at the time of deciding pairs are selected from groups
of light emission blocks A501 and groups of light emission blocks
B503.
[0119] FIG. 16 is a schematic view showing an example of groups of
light emission blocks 111 which have been selected in step S501. As
explained before, when looking at the LED backlight apparatus 101
from its front direction (from the side of the color liquid crystal
panel 105), groups of light emission blocks lying in the left half
thereof are assigned as the groups of light emission blocks A501,
and groups of light emission blocks lying in the right half thereof
are assigned as the groups of light emission blocks B503. From
among these, light emission blocks 111 at the first row from the
upper end are selected as groups of light emission blocks 111 which
become candidates at the time of deciding pairs. Specifically, four
of the light emission block 111 (1, 1, 1), the light emission block
111 (1, 1, 2), the light emission block 111 (1, 2, 1), and the
light emission block 111 (1, 2, 2) are selected from the groups of
light emission blocks A501. In addition, four of the light emission
block 111 (1, 3, 1), the light emission block 111 (1, 3, 2), the
light emission block 111 (1, 4, 1), and the light emission block
111 (1, 4, 2) are selected from the groups of light emission blocks
B503. Here, brightness detection of the four light emission blocks
111 in the groups of the light emission blocks A501, which are the
first light emission block group, is carried out by two optical
sensors (i.e., the optical sensor 113 (1, 1) and the optical sensor
113 (1, 2)) which are a first detection unit group corresponding to
the first light emission block group. In addition, brightness
detection of the four light emission blocks 111 in the groups of
the light emission blocks B503, which are the second light emission
block group, is carried out by two optical sensors (i.e., the
optical sensor 113 (1, 3) and the optical sensor 113 (1, 4)) which
are a second detection unit group corresponding to the second light
emission block group.
[0120] Then, in step S502 in FIG. 15, in those groups of light
emission blocks 111 in which pairing has not yet been made, among
the groups of light emission blocks 111 selected in step S501, (1)
a light emission block 111 in a group of light emission blocks
A501, which is the nearest to an optical sensor 113 for detection
of a group of light emission blocks B503, and (2) a light emission
block 111 in the group of light emission blocks B503, which is the
nearest to an optical sensor 113, among a plurality of optical
sensors 113 for detection of the group of light emission blocks
B503, which is the farthest from the light emission block 111 in
the group of light emission blocks A501, are decided as a pair.
[0121] FIG. 17A is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S502.
The light emission block 111 (1, 2, 2) is selected from the group
of light emission blocks A501, and the light emission block 111 (1,
4, 1) is selected from the group of light emission blocks B503.
Here, the light emission block 111 (1, 4, 2) may instead be
selected from the group of light emission blocks B503.
[0122] Thereafter, in step S503 in FIG. 15, in those groups of
light emission blocks 111 in which pairing has not yet been made,
among the groups of light emission blocks 111 selected in step
S501, (1) a light emission block 111 in a group of light emission
blocks B503, which is the nearest to an optical sensor 113 for
detection of a group of light emission blocks A501, and (2) a light
emission block 111 in the group of light emission blocks A501,
which is the nearest to an optical sensor 113, among a plurality of
optical sensors 113 for detection of the group of light emission
blocks A501, which is the farthest from the light emission block
111 in the group of light emission blocks B503, are decided as a
pair.
[0123] FIG. 17B is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S503.
The light emission block 111 (1, 3, 1) is selected from the group
of light emission blocks B503, and the light emission block 111 (1,
1, 2) is selected from the group of light emission blocks A501.
Here, the light emission block 111 (1, 1, 1) may instead be
selected from the group of light emission blocks A501.
[0124] Then, in step S504 of FIG. 15, it is determined whether all
the pairs of the light emission blocks 111 which become candidates
have been decided. In cases where all the pairs of the light
emission blocks 111 which become candidates have been decided, the
procedure of this flow chart is all completed, but in cases where
they have not yet been decided, a return is again made to step
S502.
[0125] FIG. 17C is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S502
of a second round. The light emission block 111 (1, 2, 1) is
selected from the group of light emission blocks A501, and the
light emission block 111 (1, 4, 1) is selected from the group of
light emission blocks B503.
[0126] FIG. 17D is a schematic view showing an example of light
emission blocks 111 which have been decided as a pair in step S503
of the second round. Here, there is only one light emission block
111 which has not yet been decided as a pair, in each of the group
of light emission blocks A501 and the group of light emission
blocks B503, and hence, there is no combination which makes a pair,
other than a combination of the light emission block 111 (1, 1, 1)
and the light emission block 111 (1, 3, 2).
[0127] As described above, this second embodiment can be applied,
even in cases where the number of optical sensors with respect to
the number of the light emission blocks is different from that in
the first embodiment. As a result of this, the brightnesses of a
plurality of light emission blocks 111 are detected at the same
time by the use of a plurality of optical sensors 113 in a state
where the plurality of light emission blocks 111 are caused to turn
on at the same time. At that time, detection errors will occur
because lights emitted by light emission blocks 111 other than a
light emission block 111 which is to be detected by a corresponding
optical sensor 113 enter each optical sensor 113 as leakage light.
However, it is possible to carry out calibration by causing a
plurality of light emission blocks 111 to emit light at the same
time in a combination thereof which can make such detection errors
as small as possible. Accordingly, accurate calibration can be
carried out, thus making it possible to suppress brightness
unevenness in an effective manner.
[0128] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0129] This application claims the benefit of Japanese Patent
Application No. 2012-080967, filed on Mar. 30, 2012, which is
hereby incorporated by reference herein in its entirety.
* * * * *